The present invention relates to an electronic keyboard instrument which can achieve substantially the same acoustic effects as achieved by a natural musical instrument.
Among the conventionally-known tone generation methods for electronic musical instruments are one which records waveforms of tones generated by a natural musical instrument, stores, into a waveform memory, the recorded waveforms of the tones as digital waveform data encoded by the PCM coding scheme or the like and then reads out the waveform data from the waveform memory when tones are to be generated by the electronic musical instrument.
Further, among the conventionally-known piano-type electronic keyboard instruments (hereinafter referred to as “electronic pianos”) are one which has, as a tone source, a waveform memory that records (i.e., samples) tones of an acoustic (i.e., natural) grand piano in three channels in such a manner that a set of waveform data of three channels is stored in the waveform memory per tone (or note) corresponding to a single key depression operation. More specifically, for recording a set of waveform data of three channels, a tone generated by the grand piano is stereophonically recorded, using a stereophonic pair of unidirectional or non-directional microphones, in two channels corresponding to the two microphones, and indirect sounds generated simultaneously with the piano tone and containing a resonance and the like is recorded, using a monaural non-directional microphone, in one channel.
In an electronic piano disclosed in Japanese Patent Application Laid-open Publication No. 2003-316358, which is designed to reproduce stereophonically-recorded waveform data of two channels via stereophonic two-channel speakers and reproduce one-channel indirect sound waveform data via a monaural one-channel speaker, specific installed positions of the speakers are determined with only a stereophonic effect of performed tones taken into primary account. Further, when recording stereophonic two-channel waveform data, a stereophonic pair of microphones are installed with the “off-microphone” setting, where the microphones are positioned distant from sounding sources (strings and soundboard) of the grand piano, so that stereophonic waveforms can be picked up with good balance. Further, one monaural non-directional microphone too is installed with the off-microphone setting with a view to picking up indirect sounds.
Generally, in the case of a home electronic piano, a human player of the electronic piano is an initial listener of a performed tone. Thus, for a piano tone color (e.g., grand piano tone color) of the electronic piano, it is desirable that a performed tone, particularly heard at the position of the human player (i.e., by the human player) be, a realistic reproduction of acoustic characteristics of an acoustic grand piano. However, the piano tone color (grand piano tone color) of the prior art electronic piano can not sufficiently reproduce the acoustic characteristics of the acoustic grand piano; particularly, the prior art technique can not achieve substantially the same acoustic effects as achieved by the acoustic grand piano, namely, it can not achieve a sufficient reality and depth feeling of a performed tone heard at the position of the human player.